424 ELEMENTARY BIOLOGY. [CHAP. 



remains rudimentary, and immediately gives rise to a 

 sporangium, in which the asexual conidia are produced. 



When Mucor is allowed to grow freely on such a sub- 

 stratum as bread, or at the surface of a saccharine liquid, it 

 takes on no other form than that described; but, if it be 

 submerged in the same liquid, the mode of development of 

 the younger hyphas becomes changed. They break up, by 

 a process of constriction, into short lengths, which separate, 

 acquire rounded forms, and at the same time multiply by 

 budding after the manner of Torulce. While these changes 

 are in progress, an active fermentation is excited in the 

 fluid, so that this " Mucor-Torula," functionally as well as 

 morphologically, bears a resemblance to the yeast-plant, 

 from which however its life-history shows it to be quite 

 distinct. 



If the Mucor-Torula is filtered off from the saccharine 

 solution, washed, and left to itself in moist air, the " Torulce" 

 give off very short aerial hyphae, which terminate in minute 

 sporangia. In these a very small number of ordinary 

 Mucor spores is developed, but, in essential structure, both 

 the sporangia and the spores resemble those of normal 

 Mucor. 



LABORATORY WORK. 



A. Penicillium. 



Prepare some Pasteur's fluid, and leave it exposed to 

 the air in saucers in a warm place; if Penicillium spores are 

 at hand add a few to the fluid in each' saucer: if spores 

 cannot be obtained, the fluid, if simply left to itself, will 

 probably be covered with Penicillium in ten days or a 



